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BUFFALO, N.Y. – Caffeine intake by children and
adolescents has been rising for decades, due in large part to the
popularity of caffeinated sodas and energy drinks, which now are
marketed to children as young as four. Despite this, there is
little research on the effects of caffeine on young people.

One researcher who is conducting such investigations is Jennifer
Temple, PhD, associate professor in the Department of Exercise and
Nutrition Sciences, University at Buffalo School of Public Health
and Health Professions.

Her new study finds that after puberty, boys and girls
experience different heart rate and blood pressure changes after
consuming caffeine. Girls also experience some differences in
caffeine effect during their menstrual cycles.

The study, “Cardiovascular Responses to Caffeine by Gender
and Pubertal Stage,” will be published online June 16 in the
July 2014 edition of the journal Pediatrics.

Past studies, including those by this research team, have shown
that caffeine increases blood pressure and decreases heart rate in
children, teens and adults, including pre-adolescent boys and
girls. The purpose here was to learn whether gender differences in
cardiovascular responses to caffeine emerge after puberty and if
those responses differ across phases of the menstrual cycle.

Temple says, “We found an interaction between gender and
caffeine dose, with boys having a greater response to caffeine than
girls, as well as interactions between pubertal phase, gender and
caffeine dose, with gender differences present in post-pubertal,
but not in pre-pubertal, participants.

“Finally,” she says, “we found differences in
responses to caffeine across the menstrual cycle in post-pubertal
girls, with decreases in heart rate that were greater in the
mid-luteal phase and blood pressure increases that were greater in
the mid-follicular phase of the menstrual cycle.

“In this study, we were looking exclusively into the
physical results of caffeine ingestion,” she says.

Phases of the menstrual cycle, marked by changing levels of
hormones, are the follicular phase, which begins on the first day
of menstruation and ends with ovulation, and the luteal phase,
which follows ovulation and is marked by significantly higher
levels of progesterone than the previous phase.

Future research in this area will determine the extent to which
gender differences are mediated by physiological factors such as
steroid hormone level or by differences in patterns of caffeine
use, caffeine use by peers or more autonomy and control over
beverage purchases, Temple says.

This double-blind, placebo-controlled, dose-response study was
funded by a grant from the National Institute on Drug Abuse of the
National Institutes of Health.

It examined heart rate and blood pressure before and after
administration of placebo and two doses of caffeine (1 and 2 mg/kg)
in pre-pubertal (8- to 9-year-old; n = 52) and post-pubertal (15-
to 17-year-old; n = 49) boys (n = 54) and girls (n = 47).

Co-authors are Amanda M. Ziegler, project coordinator for the
Nutrition and Health Research Lab, and graduate student Adam
Gracyzk, both in the UB Department of Exercise and Nutrition
Sciences, UB School of Public Health and Health Professions; Ashley
Bendlin, undergraduate student in the Environmental Studies Program
and the Department of Psychology, UB College of Arts and Sciences;
Theresa Sion, undergraduate student in family nursing, UB School of
Nursing; and Karina Vattana, who recently graduated with a BS in
biomedical sciences, UB School of Medicine and Biomedical
Sciences.

For an embargoed copy of the study, contact Noreen Steward, nstewart@aap.org, American
Academy of Pediatrics Department of Public Affairs. For an
interview with the lead author, contact Patricia Donovan, Office of
Communications, University at Buffalo, 716-645-4602 or pdonovan@buffalo.edu.

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